The PLATO 2.0 Mission (1310.0696v2)

Abstract: PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 sec readout cadence and 2 with 2.5 sec candence) providing a wide field-of-view (2232 deg2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50% of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0.

• The paper presents the PLATO 2.0 mission, which aims to measure exoplanet radii, masses, and ages using photometric transits and asteroseismology.
• It details a multi-telescope design with 34 cameras covering 2232 square degrees to robustly detect Earth-sized planets in habitable zones.
• The mission’s high-precision data is expected to refine stellar evolution models and improve understanding of planetary formation and habitability.

An Expert Analysis of the PLATO 2.0 Mission

The paper on the PLATO 2.0 mission extensively details the scientific goals and technical specifications of the European Space Agency’s initiative aimed at advancing our understanding of exoplanetary and stellar science. As a mission selected for the M3 launch opportunity within the Cosmic Vision 2015-2025 program, PLATO 2.0 represents a decisive step in exoplanet research, placing a distinctive emphasis on the characterization of terrestrial exoplanets and their host stars.

The PLATO 2.0 mission is designed to achieve high-precision measurements of planetary radii, masses, and ages by leveraging a large array of detectors. The mission's primary focus is on detecting terrestrial planets within the habitable zones of solar-like stars. This is particularly significant given that such discoveries offer the potential to provide insights into the formation and evolution of planetary systems that could be analogous to our own.

Instrumentation and Operational Strategy

At the core of PLATO 2.0 is a multi-telescope design consisting of 34 cameras mounted on a single payload array, providing a wide field-of-view of 2232 square degrees. This configuration allows the mission to observe a substantial fraction of the sky, targeting bright stars in the range of 4-11 magnitudes to facilitate photometric transits. The strategic design aims to ensure that data is gathered with both breadth and depth, maximizing the probability of detecting Earth-sized planets in orbits similar to our own.

Critical to the mission's success is the dual observing strategy, encompassing long-duration observations to ensure capture of transiting events on extended orbits, alongside a "step-and-stare" phase to increase sky coverage. This combination supports the comprehensive search for planets at various orbital distances and periods, enhancing PLATO 2.0’s ability to probe the diversity of exoplanetary systems.

Scientific Objectives and Methodology

The scientific premise of the PLATO 2.0 mission revolves around several key challenges in contemporary astrophysics. First, it seeks to map the occurrence rate of planets as small as Earth within the habitable zones of bright stars. This endeavor is supported by its capacity for precise measurements — with expected accuracies of 2% for radii, roughly 10% for masses, and about 10% for ages — effectively addressing limitations faced by its predecessors such as CoRoT and Kepler.

Central to the mission’s capability is the employment of asteroseismology to derive stellar parameters to high precision. This allows for a more detailed understanding of host star characteristics, subsequently leading to improved accuracy in the determination of exoplanet properties, a significant leap from existing methodologies.

PLATO 2.0 is also positioned to make substantial progress in stellar and galactic science. By analyzing stellar oscillations, the mission will contribute to enhancements in stellar evolutionary models and provide a unique dataset for the validation of theories regarding stellar structure and ages. This aspect intersects closely with the concurrent data from the Gaia mission, promising a rich legacy for astronomical research.

Expected Outcomes and Implications

PLATO 2.0 anticipates producing a catalogue of well-characterized exoplanets, which will not only provide a broader statistical basis for understanding planetary formation but also assist in the refinement of atmospheric models for terrestrial planets through subsequent spectroscopic follow-up. The mission’s results also have implications for future endeavors in direct imaging and atmospheric analysis, potentially informing criteria for habitability in exoplanetary systems.

Moreover, PLATO 2.0’s observations will aid in constraining planetary migration models and investigating phenomena such as exomoons and planetary rings, thus offering a holistic view of planetary system dynamics. The mission’s focus on nearby and bright stars lays a foundation for identifying prime targets for future exploration, including spectroscopy of planetary atmospheres.

Concluding Remarks

PLATO 2.0 is positioned to address several longstanding questions in exoplanet science and usher in a new era of exploration and discovery. By systematically characterizing planets and their stellar environments, it aligns with a broader scientific pursuit to grasp the intricacies of planetary diversity and the potential for life beyond Earth. Its contribution to the field will be far-reaching, establishing a paradigm for future missions while bolstering our understanding of planetary systems both familiar and novel.